1. Field of the Invention
This invention relates to a boot seal for a ball joint which consists of such members as a ball stud and a socket housing holding the head of the stud. More particularly it relates to a boot seal, for a ball joint, in which a ball stud inclines against a socket housing at a relatively small angle, and a relatively small clearance is allowed between a joint member connected to the shank portion of the ball stud and the socket housing confronting the joint member.
2. Description of the Prior Art
The boot seals mounted on the conventional ball joints of this type can be classified into two types. One type covers boot seals provided with a space for a grease room between the internal surface of the boot seal and the upper portion of the housing, and the other covers those without the space. The boot seal of the former type generally comprises an annular boss portion in close contact with the shank portion and a skirt portion extending downward and outward from the boss portion and covering the upper peripheral edge of the socket housing. When the boot seal of this type tilts, gaps are formed between the internal surface of the skirt portion and the upper side surface of the socket housing and between the upper surface of the boss portion and the lower surface of the joint member. A gap is also formed between the joint member and the upper surface of the boss portion on account of the abrasion and the deterioration of elasticity of the internal surface of the skirt portion. Thus foreign matters such as dust are apt to enter the ball joint through the gap. Consequently this type can be utilized usefully only where it is not covered with much dust and the like. The boot seal belonging to the second type is composed generally of a boss portion filling the space between a joint member and a socket housing almost completely and a suitable skirt portion extending outward from the boss portion. Accordingly the boot seal of this type is utilized usefully in the field of application where a means for supplying grease is already prepared at the side of ball joint. In a ball joint of the construction disclosed, for example, in U.S. Pat. No. 3,220,756, a grease nipple is provided at the side wall of the socket housing and grease can be supplied to the interior of the socket housing from the nipple. The boot seal of the second type is utilized effectively in this kind of ball joint.